*{
    margin: 0;
    padding: 0;
}
ul,ol,li{
    list-style: none;
}
ul{
    display: flex;
    margin: 50px auto;
    width: 400px;
    height:80px;
    line-height: 80px;
    text-align: center;
}
ul>li{
    background-color: orange;
    width: 80px;
    box-sizing: border-box;
    border-radius: 50%;
    color: #fff;
    cursor: pointer;
}
.active{
    background-color: skyblue;
}
ol{
    width: 400px;
    height: 320px;
    margin: auto;
}
ol li{
    width: 100%;
    height: 100%;
    text-align: center;
    display: none;
}
img{
    width: 90%;
    height: 100%;
}
.dog{
    display: block;
}